Various compression devices are known for applying compressive pressure to a patient's limb. These types of devices are used to assist mainly in the prevention of deep vein thrombosis (DVT), vascular disorders and the reduction of oedema. Prior art devices are adapted for use in a hospital setting in which they are used predominantly for the prevention of DVT in patients with a high risk for developing the same. U.S. Pat. No. 5,117,812, U.S. Pat. No. 5,022,387 and U.S. Pat. No. 5,263,473 (The Kendall Company), U.S. Pat. No. 6,231,532 (Tyco International Inc), U.S. Pat. No. 6,440,093 (McEwen et al) and U.S. Pat. No. 6,463,934 (Aircast Inc) disclose such devices.
Compression therapy is used in the treatment of venous leg ulcers. The treatment relies on the compression achieving a reduction in oedema and improved return of blood via the venous system. This in turn reduces the residence time for blood supplied to the lower limb and the severity of ischaemic episodes within the limb that can result in tissue breakdown.
Compression of the limb can be achieved by a pneumatic compression device. The known devices apply pressure to the limb through a thick cuff or cuffs which affect patient mobility and are aesthetically unacceptable to many patients. The pump that produces the compression is large and heavy and can supply fluid to the cuffs through many pipes. These characteristics make the known devices unsuitable for domestic use. It is believed that immediate mobilisation under compression post-surgery is beneficial in prevention of DVT, and existing pneumatic compression devices are unsuitable because of their size and weight, restricting patients to their beds while the treatment is applied.
Pneumatic compression devices do however have advantages. They provide an effective treatment, while deflated, the inflatable cuff or cuffs are easy to apply to the patient's leg and the pressure is more readily controlled and monitored. Also they are not subject to the effect of radius where the level of compression depends on the circumference of the limb so that high pressure occurs at the ankle and shin bones, where the radius under the bandage is reduced and low pressure spots occur in depressions such as those around the ankle. The effect of radius is a fundamental limitation of elasticated bandages and stockings.
Pneumatic compression devices do suffer from the problem that the shape and configuration of the cuff can lead to variations in pressure when the cuff is inflated. This is undesirable as in order for treatment to be most effective the whole area in need of treatment should receive compression. Most desirably the pressure distribution should be as even as possible. U.S. Pat. No. 6,494,852 to Barak describes a device which is said to be portable and ambulant. This device however comprises an inflatable sleeve with a plurality of cells arranged longitudinally along the sleeve from its distal part to its proximal part. The cells are of a simple, bag like construction which when inflated take on a cylindrical cross-sectional shape. We have found that such a shape when inflated leads to pressure high points and low points on the limb.
There thus exists a need for a cuff which gives a uniform pressure profile in the area of treatment along the limb with minimal pockets of high and low pressure when inflated.